Sustainable use of magnesite mine waste in self-compacting concrete and its study on strength, microstructure, cost and CO₂ emission

Abstract

Managing waste materials from mining is of universal interest owing to its massive volume, ecological impacts, health hazards, and disposal challenges despite high operational costs. Advancements advocate for recycling mine waste to sustainably support construction. As the construction sector heavily consumes resources, utilizing mine waste from magnesite mines (MMW) in concrete has gained attention. This experimental study assesses the viability of substituting MMW for natural fine and coarse aggregates in self-compacting concrete (SCC) at intervals of 10% up to 50% by weight. Evaluations were done on fresh (slump flow, T50 slump, V-funnel, J-ring, L-box) and hardened (compressive, splitting tensile, and flexural strength) properties, along with microstructural features, cost, and CO2 emissions. The findings unveil that nearly all mixtures exhibit commendable performance, where mine waste is replaced for fine and coarse aggregates showcasing superior fresh and hardened properties, respectively. Fresh property results reveal the SF1 flow category with VF1 and VF2 viscosity types for the SCC mixtures. Moreover, these SCC mixtures observed substantial strength enhancements of approximately 10% to 15% in compressive, splitting tensile and flexural test results at 28 and 90 days. Microstructural analysis corroborates the observed strength outcomes, indicating a denser concrete matrix. Significant environmental and economic benefits were observed, including a notable 20% reduction in CO2 emissions and 17% cost savings. These findings underscore the potential of integrating MMW into SCC mixtures as a sustainable approach towards construction materials, offering both performance and environmental advantages.